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Building the Digital Collections
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The United States and Brazil: Expanding Frontiers, Comparing Cultures digital collection comprises multiple formats from throughout the collections of the Library of Congress and its partner institution, the National Library of Brazil. The collection includes printed matter in Portuguese, English, and other languages, some foldout illustrations or maps; handwritten manuscripts; pictorial materials (mainly watercolors); and cartographic materials. The variety of original formats required specialized digitization for each format and scanning and post-processing input from many members of the Library’s Digital Conversion Group. The production of this digital collection proceeded under format digitization standards as developed by the Library of Congress's American Memory program. Specific scanning information is provided for each format.
The National Library of Brazil digitized materials from its collections according to their specifications that correspond approximately to those used by American Memory. The Library of Congress holds copies of the TIFF files produced by the National Library of Brazil and created the derivative images delivered to users on this project site.
All online items are described and searchable individually in both MARC and non-MARC bibliographic record databases. Bibliographic data supplied by the National Library of Brazil to the Library of Congress for items included in this project are presented in a non-MARC record structure but were originally created in MARC using Brazilian cataloging rules and procedures.
Specifications for Library of Congress Digitization
Printed materials in The United States and Brazil: Expanding Frontiers, Comparing Cultures were digitized onsite by the Library’s Information Technology Services (ITS) Digital Scan Center. Each item was reproduced as a facsimile page image. In order to preserve the original items, bound works were scanned in their bindings, one page at a time.
General Collections: Selected items contain textual pages (with typography and line art) and were scanned as 300 dots-per-inch (dpi) bitonal images in the TIFF format and converted using ITU Group IV compression. Reference images in GIF format were created for quick online access. These images were derived from the archive files during the post-processing phase of production.
Rare Books and Special Collections: Selected items include printed half-tone illustrations, finely detailed line drawings, or pages with significant color, including book covers. All pages were digitized as 300 dpi, 24-bit RGB color images to capture the physical nature and age of the material. Reference images in GIF format and higher quality images in JPEG format were created for quick online access. These images were derived from the archive files during the post-processing phase of production.
Several books in the collection also contain oversized foldout illustrations or maps. The Library's Conservation Division treated and prepared these pages for scanning, a process that required unfolding and flattening the pages. One book contained an image of a map that was subsequently compressed using the Multi-Resolution Seamless Image Database (MrSID) format, frequently used for stand-alone cartographic material. Although MrSID is a "lossy" compressor, the images were compressed at a ratio of 22:1 without experiencing any loss of information. This software integrates multiple resolutions of an image into a single file, which enables Internet users to zoom in for greater detail. These images are integrated with other page image formats to create a complete sequence of pages for a particular item. LizardTech donated the license for the compression software. These print materials are described in the database using pre-existing and updated MARC-format catalog records.
Manuscript materials in The United States and Brazil: Expanding Frontiers, Comparing Cultures were digitized onsite by the Library's ITS Digital Scan Center. Each item was reproduced as a facsimile page image. In order to preserve the originals, bound works were scanned in their bindings, one page at a time.
These handwritten materials were scanned in 24-bit RGB color in order to capture and display a wide range of tonal variations, ranging in quality from document paper to pencil and ink.
Reference images in GIF format and higher quality images in JPEG format were created for quick online access. These images were derived from the archive files during the post-processing phase of production.
Title constructs were created by staff specialists. Individual item-level descriptions and records were created for bibliographic image displays. Data is stored as non-MARC records and exported during data delivery. Each record has an item number, description of content, and date.
Cartographic materials from the Library's collections were created by Geography and Map Division staff who scanned original maps in 24-bit RGB color. Each raster image was produced by scanning the item at a resolution of 300 dpi and converting to TIFF format.
The TIFF files were compressed, using MrSID, a wavelet-based image compressing software.
These items are described in the database using pre-existing and updated MARC-format catalog records.
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